Small gun for perforating casing in oil wells



May 26, 1953 r. A. HUBER SMALL GUN FOR PERFORMING cAsING 1N oIL WELLSFiled sept. 11, 195o lll. $11114ltrrflflllllalllll,Iliff/116711 nZrlllllll/lllrflllllllllli l rlllllllu/III 2 Shets-Sheet l .444514rnvfrf .furl

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ATTORNEY May 26, 1953 T. A.- HUBR SMALL GUN FOR PERFORATING CASING INOIL WELLS Filed sept. 11 195o 2 Sheets-Sheet 2 A INVENTOR Theodore A.Huben, BY

, ATTORNEY.

Patented May 26, 1953 SMALL GUN FOR PRORAT'ING CASING IN OIL WELLSTheodore A. Huber, Houston, Tex., assigner, by

me'sne assignments, to Standard Oil Development Company, Elizabeth, N.Jr., a. corporation of Delaware Application September 11, 1950, `SerialNo. 1'84-,161

2 Claims. l

This invention relates to guns for perf'orating pipe `in oil wells orthe like and more particularly to guns which are small enough to runthrough tubing in `a well for perforating casing beneath the tubing.

Guns vand Iearplc'isives have long been used for pericia-ting casing inoil wells and the art is well developed. As commonly constructed thebarrels of guns used for such purposes are fixed hori- 'zontally in acarriage and these barrels approach in length, as far 'as is practical,the diameter of the 'casing -so as to obtain the maximum fire poweri If'shaped charges of explosives are used instead of guns which firebullets, these also have been fixed in a carriage `or gun body. Evenunder' the best conditions, effective perforation of oil well casing,and the cement which usually surrounds it, is difficult to accomplish,and since the `size of the gun 'or explosive is important, casingperforators used heretofore have not been run into the well throughtubing or other pipe smaller 4in diameter than the casing.

It has recently been proposed to perform certain operations includingthe perforating of casing in an foil Well while tubing is in it; See forexample application of Theodore A. 'Huber Serial No. 133,025, ledDecember 15, 1949, for Method of Completing and Repairing Oil Wellswhere the use of a casing perforating gun capable of being ruin throughtubing is required. Large l savings in time and cost can be effected inthis way if eirective perforation can be accomplished.

Small guns are, of course, old in the art and eve'n iff they were not,no invention would be n- 4volved in merely changing the dimensions ofknown guns. But from experience it has been round that, in order tosolve the problem of perforating casing beneath tubing in the well, moremust be `done 'than merely provide a' small diamete'r gun and guncarriage, for small guns have barrels too short to provide adecua-tering power unless they are placed in a position close to their targetswhen they are iired.

In accordance with the present invention, it is proposed to solve theproblem of providing effective firing power to perforate casing with anassembly which is run into and out of the well `through tubing byarranging the guns in their vcarriage on trunnions and by providingmeans `for rotating them from the vertical positions which they occupywhile being lowered into the well, into horizontal iring positions.Inasmuch 'ae the guns may be 'iire'd by electricity, it iis convenientto employ an electric motor to rotate them exactly the right amount. Itis also 2 venient to employ limit switches to cause the ring to occurwhen the barrels are horizontal and to return the guns .to verticalposition so that they 'can be retrieved from the well if they are notdestroyed upon lirng.

The objects 'of the invention will be apparent from the followingdescription, taken in connection with the accompanying drawings, inwhich:

Fig. 1 is a view in vertical ycrosshseetion `of a portion of an yoilwell with a Ygun being lowered through tubing therein` Fig. 2 isasimilar view of a lower portion of the 'well 'of Fig. l with the gunthereof in firing position.

Fig. 3 is a similar view of the portion of the well of 2 showing howbullets are red from the gun into the earth formations.

Fig. 4 is a similar view of the portion of the well of Fig. 3 showingthe Igun being retrieved through the casing.

Fig. 5 is asimilar view of the lower portion of an oil well lshowing howshaped charge explosives may be employed to carry out the principles 'ofthe invention instead of a bullet gun.

Fig. 6 is a similar View showing how a gun using shaped charges may beretrieved through tubing in the well.

Fig. 7 is an enlarged fragmentary view, partly in orossseetion of a gunsomewhat Ysimilar to that illustrated in Figs. 1 to 4 and illustratingone system for rotating the gun barrels and 4for firing the guns whenthey are in the desired po- Sition.

Fig. 8 is a transverse cross-sectional view of the gun of Fig. '7showing a detail of the driving mechanism for rotating the guns, theView being taken on the line 8-1-8 thereof.

Fig. 9 is a transverse cross-sectional view of the gun of Fig. 7 showinga detail of the limit switch employed, the view beiner taken on the line3d-9 thereof.

Fig. 10 is a transverse cross-sectional view of the gun of Fig. '7showing a detail of the trunnions and driving mechanism, the view beingtaken on the line Illl0 thereof.

Fig. 1l is a `circuit diagram of the gun of Fig. 7.

Referring to the drawings in detail and first to Figs. 1 to i whichillustrate a sequence of operation of a gun constructed in accordancewith the principles of the invention, it will be seen that the casing efan oil well is there shown at l2. A tubing i3 is positioned in the wellwith its 'lower end above the portion of the 'casing which is to beperforated, as shown in Figs. 2, 3, and 4.

Within the tubing i3., as shown in rig. l and of steel and it is ofcylindrical shape with anumber of slots I6 provided transversely toaccommodate gun barrels I1 which are mounted for rotation in the slotsI6 by trunnions I8.

The gun barrels I1 are of a length greater than the diameter of thetubing I3 and only slightly less than the diameter of the casing I2. Inorder for them to be lowered into the well through the tubing, it isnecessary that they be held in a vertical position as shown in Fig. 1.After the carriage has passed out of the bottom of the tubing, thebarrels I1 may be rotated to the horizontal position as shown in Fig. 2.The carriage I4 can then be raised and lowered by the cable I5 and theguns red individually at different depths, or all of the guns may be redat the same time, or nearly so, in accordance -with well'knownperforating technique.

If the guns are of the type which shoot bullets,

each barrel I1 may be loaded at both ends with -crease the effective gunbarrel length and secure greater penetration, as described hereinafterand 'shown in Fig. 7.

After the bullets have been red, the barrels I1 may be rotated back intothe vertical position as shown inFig. 4, so that they can be pulledbac-k up through the tubing I3 from the well.

Mechanism including areversing screw like the to remove them-level-Winder on a fishing reel may readily be provided by those skilledin the art for causing the barrels to reverse their direction ofrotation after firing. Provision of such means for reversing directionenables the use of a stronger gun body or carriage, because the slots I6there- 'in may then be reenforced along one side at the top and one sideat the bottom. However, in the arrangement described hereinafter andshown in Figs. 7 to 10, the barrels rotate a total of 180 degrees and donot reverse their direction of rotation. In any event the guns are redafter they are rotated 90 degrees, or approximately so.

If shaped charges of explosive are used to perforate the casing, or 'ifthe gun or explosive is otherwise designed to concentrate the force ofthe explosion upon points opposite the ends of the gun, as taught in theMims Patent 1,582,184, it may be convenient to have the barrels blow upas shown in Fig. 5. Fragments of the barrels Aare there shown at 22 andholes in the casing -and earth formation are shown at 23.

The gun carriage I4 then comes back out of the well empty, as shown inFig. 6. y

Figs. 7 to 10 of the drawing show one way of rotating the barrels I1 ontheir trunnions I8. In Fig. 7, the barrels I1 are shown as bullet gunswith one bulletl 24 in each barrel. It will be observed that the mouthof upper barrel I1 shown in Fig. 7 is at the top while the mouth of thelower barrel I1 is at the bottom when the barrels are in theirrunning-in (full line in Fig. 7) position. The barrels may be thusalternately positioned. Since all the barrelsrotate @Gunterclockwise, asviewed in Fig. 7, when they take their horizontal positions, as shown indotted lines, the upper barrel I1 will re bo the left while the lowerone Will re to the right. The same staggering of the perforations, thatis, one to the right and one tothe left could be obtained by loading allthe barrels alike, say with their muzzles pointing upwardly, in the fullline position of Fig. 7 and by causing alternate ones to rotate inopposite directions, that is, half clockwise and half counter-clockwise.

For rotating the barrels, one trunnion I8 of each barrel may be providedwith ka gear 25 driven by a Worm 26 on a shaft 21 which extendsdownwardly through the carriage I4 from a chamber at the top. Alternateworms 26. may be right and left hand screws, if desired, to cause halfof the barrels to rotate in opposite directions. Within the chamber is`an electric motor 28, connected to the shaft 21 by suitable gears 29and 30.

Also within the chamber in the top of the carriage I4 are two limitswitches, the blades 3I and 32 of which are insulated and mounted on arider 33 which is threaded upon a screw 34 connected to the shaft of themotor 28. The blade 3| engages a ground bar 35 over most of the path oftravel of the rider 33. This blade is in the circuit for the motor andthe length of the ground bar 35 is such, and the pitch of the screw 34is such that the barrels I1 rotate 180 degrees from the position shownin full lines in Fig. 7 before the blade 3| leaves the lower end of theground bar 35. `When it does leave, the circuit of the motor 28 isbroken and the rotation of the barrels I1 cease.

The blade 32 is designed to strike an insulated contact 36 at a timewhen the rider 33 has traveled half way from the position shown to thepoint where blade 31 leaves the ground bar 35. The contact 3G isconnected to the ring fuses of the guns, so that they reautomaticallyvwhen the barrels I1 have rotated 90 degrees from theirvertical position.

Electric current is supplied to the motor 28 and vthe fuses of the gunsthrough a conductor in the cable I5. The circuit may be like that shownin Fig. 11. As there shown, the conductor 31 of the' cable has a switch38 at the surface of the ground in series with the source of current 39.One pole of the source 39 is grounded as shown at 40 so that if oneterminal of thevmotor 23 is grounded in the well bore, the motor isenergized. This grounding occurs so long as blade 3l is engaging groundbar 35, which may be connected to the carriage I4 which is located inthe mud or other fluid in the well bore or in contact with the casing ofthe well. Until the switch 38 is closed at the surface of the ground, nocurrent can pass down the cable however so the barrels I1 are notrotated until the carriage is in the desired position in the well bore.The conductor 31 of the cable I5 is also connected to the blade 32.Hence when blade 32 engages contact 36, the fuses 4I of the guns areenergized vby thesource 39, assuming the switch 38 remains closed.

While only a few embodiments of the invention have been shown anddescribedv herein, it is obvious that changes may be made Withoutdeparting from the spirit of the invention or the scope of the annexedclaims.

What I desire to claim is:

1. In an arrangement for perforating casing in oil wells or the like, anelongated carriage small enough in diameter to enable it to be run intothe Well through tubing inside the casing to be perforated, a pluralityof guns mounted individually for rotation in said carriage, each of saidguns having a diameter less than the diameter of the tubing and a lengthgreaterL than the diameter of the tubing but less than the diameter ofthe casingI and means for rotating said guns simultaneously from theirvertical position longitudinal of the carriage into a positiontransverse the'reof, each of said guns being loaded with only onebullet, alternate guns being positioned with their muzzles at oppositeends so that when the guns are rotated in the same direction of rotationto their horizontal positions, adjacent gunswill be facing in oppositedirections, thereby being in a position to perforate the casing withstaggered holes when said guns are fired.

2. In an arrangement for perforating casing in oil Wells or the like, anelongated carriage small enough in diameter to enable it to be run intothe well through tubing inside the casing to be perforated, a pluralityof guns mounted individually for rotation in said carriage, each of saidguns having a diameter less than the diameter of the tubing and a lengthgreater than the di- 4ameter of the tubing but less than the diameter ofthe casing to be perforated, means for rotating said guns simultaneouslyfrom vertical positions longitudinal of the carriage through arcs of 180to second vertical positions longitudinal of the carriage, and means forfiring the guns at a time when they have traversed approximatelyone-half of their 180 arcs of travel, each of said guns being loadedwith one bullet, alternate guns being positioned with their muzzles atopposite ends so that when the guns are rotated in the same direction ofrotation over their arcs and fired, they will be facing in oppositedirections, thereby perforating the casing with staggered holes.

THEODORE A. HUBER.

References Cited in the le of this patent UNITED STATES PATENTS NumberName Date 1,582,184 Mims Apr. 27, 1926 2,013,457 Burt Sept. 3, 19352,198,821 Jessup Apr. 30, 1940 2,334,428 Miller Nov. 16, 1943 2,543,814Thompson Mar. 6, 1951

